ANDERvSON — THE BIRDS OF IOWA. 133 



make that hawk appear ahiiost abundant, while a dozen Chipping 

 Sparrows or Robins in that same township would be almost rare 

 for these species." 



BREEDING. 



While, in general, the presence of individuals of a species in a 

 given locality during the sunnner is considered indicative of their 

 breeding there, sttch evidence is not alwa)'S to be taken a'-, prima 

 facie proof of the fact. Many unmated birds wander far from 

 their usual summer habitat, and wounded birds may be unable to 

 make the journey northward in spring. Various species of Sand- 

 pipers linger in the Northern Iowa marshes until after June i, and 

 large numbers frequently move southward into the state early in 

 July. Some of the southern species of Herons frequently wander 

 far north of their breeding range in late summer and early autumn. 

 Many species, notably among the Ducks and Geese, which are 

 known to have nested commonly in Iowa a few years ago, ver}^ 

 seldom do so at the present time. On the other hand, the exten- 

 sive planting of groves in treeless prairie regions has induced 

 many woodland species to make their summer homes in localities 

 where they were absent a few years ago. Therefore, generaliza- 

 tions in the matter of nesting habits become very difficult, owing 

 to the rapid and complicating change of conditions, and deduc- 

 tions based upon the records of a few years ago are apt to be 

 erroneous and misleading. 



FOOD. 



The question of the food of birds is one which is probabU- of 

 the most importance economically. It is universally conceded 

 that the great majority of species are directly beneficial, and in 

 many cases indispensable, to agriculture and horticulture, either 

 by destroying noxious insects or the seeds of weeds, while but 

 a few are directly injurious b)' feeding upon fruits and grains, 

 preying upon poultry, game birds, and valuable small birds, or 

 indirectly by destroying insects which are in some measure bene- 

 ficial to agriculture. Kven those birds which are generally 

 regarded as injurious, as the Hawks and Owls, have been proved 

 to more than balance their account by the destruction of multi- 

 tudes of the vermin which prey upon the crops of the farmer. A 



[Proc. D. A. S., Vni,. XI.J 20 (August I, 1906. 1 



